Power flow in 2nd gear, function - GF27.10-P-3012ACS

TRANSMISSION 722.649 in MODEL 216.3 as of Model Year 09 /YoM 08

TRANSMISSION 722.649 in MODEL 221.1 as of Model Year 09 /YoM 08

Sectional view of automatic transmission

Fig 1: Identifying Sectional View Of Power Flow In 2Nd Gear

Courtesy of MERCEDES-BENZ USA

Fig 2: Identifying 2Nd Gear Power Flow Diagram

Courtesy of MERCEDES-BENZ USA

Shown here, power flow

Function requirements for power flow in 2nd gear, general

Circuit 87 ON
Engine running

Power flow in 2nd gear, general

The drive shaft (1) uses the center and rear planetary gear sets to increase the torque developed by the torque converter and transmit it to the transmission output shaft (5).

The following multidisk brakes, multidisk clutches and overrunning clutches are not engaged:

Multidisk brake B1 (21)
Multidisk brake B3 (23)
Overrunning clutch F1 (27)
Multidisk clutch K2 (25)

In 2nd gear, the power flows through the following gear sets:

Front planetary
Rear planetary gear set
Center planetary gear set

Front planetary

The planet carrier (29/3) and sun gear (29/1) are rigidly connected to each other via the engaged multidisk clutch K1 (24). The front planetary gear set is thereby locked and, due to the mechanical connection between the ring gear (29/4) and drive shaft (1), rotates at the transmission input speed (B) as a closed assembly.

Rear planetary gear set

The ring gear (31/4) rotates at the transmission input speed (B) due to the mechanical connection to the planet carrier (29/3). In acceleration mode , the sun gear (31/1) is supported at the transmission housing via the engaged multidisk brake B2 (22) and locked overrunning clutch F2 (28). In deceleration mode , the sun gear (31/1) is supported at the transmission housing via the engaged multidisk brake B2 (22) and the engaged multidisk clutch K3 (26). The planetary gears (31/2) roll on the fixed sun gear (31/1) and take care of a torque increase when the power is transmitted from the ring gear (31/4) to the planet carrier (31/3). The planet carrier (31/3) moves at reduced transmission input speed (B) in the direction of engine rotation.

Center planetary gear set

Due to the mechanical connection the ring gear (30/4) is driven at the same rotational speed as the planet carrier (31/3). The sun gear is supported on the transmission housing via the multidisk brake B2 (22)30/1

The planetary gears (30/2) roll on the fixed sun gear (30/1) and take care of a torque increase when power is transmitted from the ring gear (30/4) to the planet carrier (30/3). The transmission output shaft (5) connected to the planet carrier (30/3) rotates at reduced transmission input speed (B) in the direction of engine rotation.